SIP/MGCP which layer

hendychow

Hi,

1. I am confused about SIP/MGCP located on which layer.
some source said It is located on layer 7, some says on layer 5 (session layer).

2. Do we use OSI model for Voip or TCP/IP or doesn't matter ?
Is the OSI model only logical or It "really exist" ?

3. Serial interface is located at which interface ?
When I studied CVOICE, It covered about configuring ISDN :
isdn switch-type primary-qsig

controller t1 0/0
pri-group timeslots 1-23

interface serial 0/0:23
isdn incoming-voice voice

Could you tell me on which layer those command are located ?
Is it on Layer 1 ?


4. When I learned CVOICE. It also mention about VoFR (Voice over Frame Relay)
What's the difference between VoFR and Voip ?
VoFR means Voice over Frame relay or Voice over IP over Frame Relay ?

I only know that Frame relay is on Layer 2 and IP is on Layer 3

Please solve the puzzle..


Thank You very Much